526 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



de-differentiation. During the first mitosis the fibrils are dissociated 

 and are gradually dissolved. In the less differentiated element the 

 cytoplasm is itself aide to destroy the specific differentiation. 



Nerve-endings in Chelonia.* — E. Hulanicka describes the various 

 kinds of nerve-endings in the tongue, the jaws, and the skin of Testudo 

 grseca and Emys lutaria. She deals especially with the tactile cells of 

 the epidermis, and the taste-buds on the tongue and on the margin of 

 the mouth. In hibernating specimens those on the margin of the mouth 

 sink into the deeper parts of the epithelium, like the sensory buds of 

 the newt. 



Comparative Study of Heart-muscle.f — W. Lange has made a 

 study of the heart-muscle in a variety of Vertebrate types, from Fishes 

 to Mammals, with particular reference to the question of the myogenic 

 or neurogenic nature of the heart-beat. He discusses the histological 

 and embryological facts. In all classes of Vertebrates there is a 

 muscular basis for the transmission of stimuli. Pnrkinje's fibres are not 

 remains of embryonic muscle-cells. Even in very young Mammalian 

 embryos they are clearly distinguishable. They form a sarcoplasmic 

 reticulum, consisting of fibrils disposed in elongated strands or roundish 

 cell-like bodies. They contribute to the syncytial character of the 

 Vertebrate heart and to the non-nervous apparatus for conducting 

 stimuli. The Vertebrate heart-beat is myogenic ; the Invertebrate heart- 

 beat is neurogenic. 



'£> v 



Comparative Embryology, Anatomy, and Histology of the Ver- 

 tebrate Heart-! — G. Favaro deals with a representative series of hearts 

 — e.g. lamprey, hag, dogfish, sturgeon, frog, newt, tortoise, lizard, snake, 

 crocodile, bird, guinea-pig, mole, bat, and monkey — and discusses them 

 comparatively. He proposes to follow this up with a volume on the 

 human heart. He pays particular attention to the endocardium. In 

 his view the endocardium corresponds to the intima plus the media ; the 

 interstitial connective-tissue and the immediate envelope of the myo- 

 cardium, to the adventitia. Thus the heart has four, not three envelopes 

 or layers. Compared with the peripheral blood-vessels, the heart is 

 distinctive in its external layer, which has cross-striped muscle. 



Lymphatic Nodules of Birds. § — H. Further has made a study of 

 the lymphatic nodules of bir,ds. So far, these nodules have not been 

 demonstrated for all birds, but they appear to occur in water, marsh, 

 and shore-birds irrespective of their systematic position. The Anatidse, 

 which were specially investigated, have two pairs of true lymphatic 

 nodules, which are spindle-shaped structures of considerable size occur- 



* Anat. Anzeig., xlvi. (1914) pp. 485-90 (1 pi. and 3 figs.). 

 t Arch. Mikr. Anat., lxxxiv. (1914) lte Abt., pp. 215-62 (2 pis.). 

 X Ricerohe embriolog. ed. anat. intorno al cuore dei Vertebrati. Part I (1913, 

 Padova) 563 pp. (272 figs.). 



§ Jen. Zeitschr. Naturw., 1. (1913) pp. 359-410 (2 pis. and 15 figs.). 



